Just three days after adding crash protection to Firefox, Mozilla rushed out another release on Friday because people playing Farmville complained that their browser was shutting down the Facebook game.

Mozilla added what it calls "out of process plug-ins" (OOPP) -- a feature designed to keep the browser up and running when a plug-in crashes -- to Firefox 3.6.4, which shipped June 22.

If Adobe's Flash Player, Apple's QuickTime or Microsoft's Silverlight crashes or is unresponsive for more than 10 seconds, Firefox 3.6.4 displays a message telling the user that the browser has killed the plug-in.

But the 10-second pause was too short.

"Following the release of Firefox 3.6.4 we heard from some users, mainly those using older computers, that they sometimes expect longer periods of non-responsiveness from plug-ins, especially with games," said Mike Beltzner, the director of Firefox, in a post to the Mozilla blog Friday. "For these users, the default timeout of 10 seconds was too short."

Mozilla addressed the issue by bumping up the wait-to-terminate period to 45 seconds in Firefox 3.6.6, which launched June 25.

According to messages on Bugzilla, Mozilla's bug-tracking database, the change was largely driven by gripes from users playing the popular Web-based Farmville game. Farmville is a Flash-based game by San Francisco-based developer Zynga.

"Now that (Firefox) 3.6.4 has shipped, we are seeing an increasing number of reports that some users are unable to play Farmville, because Farmville hangs the browser long enough for our timeout to trigger and kill it," said Mozilla developer Justin Dolske in a Bugzilla entry Friday night. "Let's hit this with a big hammer and make it 45 (seconds)."

Mike Shaver, Mozilla's head of engineering, agreed. "There's a massive regression in user experience for a meaningful number of users of an extremely popular property, and that a raised timeout remedies it," said Shaver in a follow-up Bugzilla message. "For now we need to get out of a bad hole before it gets any worse."

Although complaints about Firefox's quick killing of hung plug-ins were not limited to Farmville, that game was the squeaky wheel that got the update grease.

"A lot of people play Farmville. To ignore those people for any length of time could have a significant effect on Firefox's share of browser users," said Firefox user Jeff Rivett on Bugzilla Sunday. "The problem already existed, but the perceived impact suddenly changed, giving it a much higher priority."

Users can update to Firefox 3.6.6 by downloading the new edition or by selecting "Check for Updates" from the Help menu in the browser.

Another solution, suggested Mozilla, is to completely disable OOPP. A support document spells out the steps users must take to kill crash protection.